1. Field of the Invention
The present invention relates to a cassette having a radiation detector for detecting a radiation that has passed through a subject and converting the detected radiation into radiation image information.
2. Description of the Related Art
In the medical field, there have widely been used radiation image capturing apparatus which apply a radiation to a subject and guide the radiation that has passed through the subject to a radiation detector, which captures a radiation image from the radiation. Known forms of the radiation detector include a conventional radiation film for recording a radiation image by way of exposure, and a stimulable phosphor panel for storing radiation energy representing a radiation image in a phosphor and reproducing the radiation image as stimulated light by applying stimulating light to the phosphor. The radiation film with the recorded radiation image is supplied to a developing device to develop the radiation, or the stimulable phosphor panel is supplied to a reading device in order to read the radiation image as a visible image.
In an operating room or the like, it is necessary to read a recorded radiation image immediately from a radiation detector after the radiation image has been captured, for the purpose of quickly and appropriately treating the patient. As a radiation detector which meets such a requirement, there has been developed a radiation detector having a solid-state detector for converting radiation directly into electric signals or for converting radiation into visible light with a scintillator and then converting the visible light into electric signals, so as to read the detected radiation image.
As shown in FIG. 12 of the accompanying drawings, Japanese Laid-Open Patent Publication No. 2004-173907 discloses a cassette (electronic cassette) 306 having a battery 304 and an image memory 305 and connected to a cable 302 having a connector 300. It also discloses an X-ray image capturing system in which a connector 310 on a cable 308 or a wireless module 330 is connected to the connector 300, a controller 314 with a power supply 312 is connected to the connector 300 by the cable 308 or a wireless terminal 322, and an X-ray generator 318 having an X-ray bulb 317 is connected to the controller 314 by a cable 316. The controller 314 is combined with a monitor 320 for displaying captured images and a storage 338 for storing captured images.
The technology disclosed in Japanese Laid-Open Patent Publication No. 2004-173907 is problematic in that the cable 302 connected to the cassette 306 is cumbersome when the cassette 306 is carried around.
Japanese Patent No. 3494683 discloses a cassette which transmits captured radiation image information to a controller by way of wireless communications. According to the technology disclosed in Japanese Patent No. 3494683, no cumbersome cable is connected to the cassette.
According to Japanese Patent No. 3494683, no cumbersome cable is connected to the cassette as image data are transmitted from the cassette to the controller by way of wireless communications. However, when the cassette communicates with the controller after the cassette is set between a patient to be imaged and a bed on which the patient lies, if the directivity of an antenna of the cassette and the directivity of an antenna of the controller are not aligned with each other, then the transmission and reception sensitivity of the cassette and the controller is greatly reduced. One solution is to increase the intensity of a radio wave transmitted from the antenna of the cassette. The increased intensity of the radio wave transmitted from the antenna of the cassette necessarily results in an increase in the power consumption of the cassette.
Particularly, after the cassette disclosed in Japanese Patent No. 3494683 is set between the patient and the bed, it is difficult to change the orientation of the cassette for increasing the transmission and reception sensitivity of the cassette and the controller. If the patient on the bed is seriously ill or an aged person, then it is all the more difficult to change the orientation of the cassette.
There is nothing disclosed in Japanese Laid-Open Patent Publication No. 2004-173907 for matching the directivity between the wireless module 330 and the wireless terminal 322.